1. Field of the Invention
This invention relates to engine test equipment and, more particularly, to a single device that is capable of selectively producing pressure in and evacuating a space.
2. Background Art
In gasoline powered engines, compression of a fuel/air mixture takes place in a crank case. To optimize engine performance, the crank case is tightly sealed. A leaking crank case may result in power loss and/or fuel leakage.
To test for proper sealing of a crank case, generally two types of tests are performed. The first of these, a pressure test, is carried out after first removing the spark plug, carburetor and muffler and sealingly covering the ports through which theses parts communicate with the inside of the crank case. A special fitting is threaded into the spark plug opening and has an adapter to accept a conduit. A predetermined pressure is developed in the crank case by a pump which forces air through the conduit attached to the spark plug fitting. The existence of leaks can be detected if the crank case will not maintain the predetermined pressure.
In some instances, crank case seals will withstand forces developed in a pressure test, yet will fail to block the entry of external air with the crank case evacuated. Accordingly, it is a general practice to perform both pressure and vacuum tests. The vacuum test is conducted in much the same manner as the pressure test, however an evacuating device is used instead of the pressure producing device.
As a general rule, separate evacuating and pressure producing devices are utilized in performing the separate tests, requiring one to keep both devices on hand at all times. From a user's standpoint, it is expensive and inconvenient to have to purchase and handle two separate devices.